目的 观察自发性高血压大鼠(SHR)大脑中动脉血管肌源性紧张度的时程变化.方法 选择SHR 32只,随机分为8、12、16、20周龄组,每组8只;另选Wistar大鼠32只按照SHR分组原则分为8、12、16、20周龄对照组,每组8只.测量不同管腔压力下主动态血管内径和被动态血管内径.观察各周龄组大鼠血管肌源性紧张度变化与血压的关系.结果 与不同用龄对照组比较,不同用龄SHR组尾动脉压、血管肌源性紧张度明显升高.8、12、16周龄SHR组血管肌源性紧张度随大鼠周龄增加而缓慢单调增加,20周龄SHR组较16周龄SHR组明显下降;不同周龄SHR组尾动脉压随大鼠周龄增加而缓慢单调增加,与16周龄SHR组比较,20周龄SHR组尾动脉压明显增加(P＜0.01).结论 血管肌源性紧张度作用参与了高血压发生、发展的整个过程.%Objective To investigate the time course of changes in myogenic tone of middle cerebral artery(MCA) of spontaneously hypertensive rat(SHR). Methods Thirty-two SHR were randomly divided into four groups(8 weeks, 12 weeks, 16 weeks, 20 weeks), and 32 sex-and age-matched Wistar rats were assigned to control groups(CON) . At the end of age of each group,segments of middle cerebral artery were isolated and cannulated to two pipettes. Vascular diameters in response to increased intraluminal pressure of isolated middle cerebral arteries under no-flow conditions were recorded by a Pressure Myograph System both in physiologic salt solution(active diameter,Da) and calcium-free physiologic salt solution(passive diameter,Dp). Results The tail artery pressure and vascular myogenic tone in SHR group was significantly higher than those in CON group. Before 16 weeks, the vascular myogenic tone of MCA in SHR group increased monotonically, but at the end of 20 weeks, the vascular myogenic tone decreased in comparison with that in 16 week-group,but still significantly higher than that in CON group. The tail arterial pressure in SHR group slowly increased monotonically with increasing weeks of age. The tail arterial pressure in 20 week-group remained significantly higher compared with that in 16 week-group. Conclusion Vascular myogenic tone participates in the whole process of hypertension.
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